Pathophysiology

The ideal scar is narrow and fills but does not eclipse the original volume of the wound bed. In fact, the wound often decreases in size upon healing due to contractile forces involved in scar formation. Occasionally, scar formation may be exuberant, as in the cases of hypertrophic scarring or keloid formation. Although discussed in detail in Keloid and Hypertrophic Scar, a brief mention of these unwelcome sequelae of wound healing is warranted.

Hypertrophic scars do not extend beyond the original boundaries of the wound laterally, but scar tissue may rise above the level of the surrounding skin. This commonly results in a very noticeable, irregularly contoured scar. A more extreme example of exuberant growth of scar tissue is the keloid. Keloid scars extend beyond the original borders of the wound, resulting in a raised and expanded scar relative to the original defect. These are often very noticeable, and they occur with increased frequency in persons with dark complexions. In both hypertrophic scars and keloids, components of the extracellular matrix are increased. Thus, while the number of fibroblasts present is normal, the cells present are apparently overactive in their wound healing response.